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Superhydrophobic starch-based films were prepared using poly­(dimethylsiloxane) (PDMS) and ball-milled montmorillonite (MMT) coating. The hydrophilic and moisture-sensitive starch-based films coated with PDMS could create a hydrophobic surface with a static contact angle of water up to 115.2 ± 1.2° but could not achieve superhydrophobic behavior. On the other hand, the starch-based film sprayed with MMT could achieve superhydrophobic behavior, but the adhesion between the starch matrix and MMT was weak. In this work, a spraying–immersion method was developed for coating starch film with PDMS and ball-milled MMT. The surface of the treated starch-based film had a contact angle of up to 159.1° and a sliding angle of 3.6°. SEM, TEM, XRD, particle size analysis, and optical profilometry were used to study the effects of PDMS and MMT on the surface properties of starch-based film, in particular PDMS/MMT ratio, MMT particle size, and preparation technologies. The results show that the hierarchical structure obtained by PDMS assisted by ball milling MMT provides the appropriate roughness to create low hysteresis superhydrophobic starch film. Increasing ball-milling time could increase the surface area and roughness, which results in increasing contact angle.

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In this work, the saccharides with different structures and molecular weights were evaluated as a plasticizer for starch-based materials, in which the saccharides from monosaccharides, such as glucose, mannose, fructose, xylose, and disaccharides including sucrose and maltose, to dextrin with different molecular weights, were used. As expected, starch and these saccharides are fully compactable and miscible since they have similar chemical components. These saccharides must work together with water or polyols to act as co-plasticizers since they are all in solid-state under dry conditions. Many monosaccharides or disaccharides with ring structures can stably stay in the starch matrix without affecting the microstructures of the polymer chains significantly, but the monosaccharides with linear structures, such as fructose and xylose, showed much more efficiency to destroy the ordered structures and enhance the movement of polymer chains, which results in higher efficiency of plasticization. All these saccharides can generally increase the stability of moisture containing in the starches because of the strong bonding by hydroxyl groups. Thermal properties of the starch-based films were investigated by differential scanning calorimetry, thermal-gravimetric analysis, and dynamic mechanical analysis, and morphologies and microstructures of the films were studied by scanning electron microscopy and X-ray diffraction. These saccharides did not affect the gelatinization temperature of the starch. Both T g and crystallinity of starch were decreased with additional saccharides, indicating that the rigid crystalline range in starch was destroyed. This research not only increased the knowledge of the plasticizing mechanism but also can be used for developing various starch-based products, including food and packaging.